Press brakes are commonly used to bend or otherwise deform sheet-like workpieces, such as sheet metal workpieces. A conventional press brake has an upper beam and a lower beam, at least one of which is movable toward and away from the other. Typically, the upper beam is movable vertically while the lower beam is fixed in a stationary position. It is common for a male forming punch and a female forming die to be mounted respectively on the upper and lower beams of a press brake.
Typically, the punch has a downwardly-oriented, workpiece-deforming surface (or “tip”). The configuration of this surface is dictated by the shape into which it is desired to deform a workpiece. The die typically has a recess, bounded by one or more workpiece-deforming surfaces, that is aligned with the tip of the punch. The configuration of this recess corresponds to the configuration of the punch's tip. Thus, when the beams are brought together, a workpiece between them is pressed by the punch into the die to give the workpiece a desired deformation (e.g., a desired bend).
From time to time, it is necessary to exchange punches and dies to accommodate different bending operations. The manner in which punches and dies are mounted on, and dismounted from, a press brake depends upon the type of tool holder being used. A variety of press brake tool holders have been devised with the goal of facilitating easy mounting and dismounting of forming tools. Exemplary tool holders will now be described.
U.S. Pat. No. 4,993,255 (issued to Treillet), the entire contents of which are incorporated herein by reference, discloses a tool holder that is attached by means of a C clamp to the bed of the upper table. Through use of a camming mechanism, the upwardly extending shank of a tool is captured between a pivotable clamp and a portion of the holder, the shank and clamp having cooperating surfaces enabling the tool to be readily inserted in the holder. In this patent, a locking cam is disclosed for locking the clamp against the tool.
U.S. Pat. Nos. 5,513,514, 5,511,407, and 5,572,902 (each issued to Kawano), and European patent publication 0 644 002 A2, the entire contents of each of which are incorporated herein by reference, all show tool holders in which a pivoting clamp is employed to secure the shank of a tool against the mounting plate of a tool holder. In these patents, the tool holder is equipped with a threaded mechanism operated by a lever that pivots from side to side to lock and unlock the clamp, force being transmitted from the lever to the clamp via a spring structure.
U.S. Pat. No. 6,003,360 (issued to Runk et al.) provides a particularly advantageous press brake tool holder. The tool holder includes a clamp that opens to a position allowing manual removal of the tool while preventing the tool from falling. The clamp in certain preferred embodiments is actuated with a manual lever. The entire contents of this '360 Runk patent are incorporated herein by reference.
U.S. Pat. No. 6,151,951 (issued to Kawano), the entire contents of which are incorporated herein by reference, discloses a tool holder having multiple hydraulically actuated pistons that transmit force generated by hydraulic fluid to a clamp. The pistons are displaced outwardly to force the clamp shut.
U.S. Pat. No. 6,564,611 (issued to Harrington et al.) discloses various hydraulic press brake tool holders. The press brake tool holders are configured for releasing and securing tools in response to applied fluid pressure. One disclosed tool holder embodiment includes a horizontally-elongated body having a longitudinal bore in which a cam shaft is slidably received. The cam shaft can have at least one axial camming surface, with a large outer diameter region axially tapered to a small outer diameter region. The shaft can be operably coupled with a cam follower pin slidably received in a bore extending transversely through the body. The cam follower pin can bear against a pivotally mounted clamp disposed about the body. In response to applied fluid pressure, the camming surface can slide axially, thereby increasing the effective outer diameter as seen by the cam follower pin, urging the cam follower pin outward and against the upper portion of the pivotally mounted clamp, thereby forcing the lower clamp portion to close upon the tang of a press brake tool. The entire contents of this Harrington '611 patent are incorporated herein by reference.
U.S. patent application publication 2004/0187552A1 (Enderlink) discloses a press brake clamping system in which a moveable horizontal pin can be clamped forcibly against the tang of a press brake tool. The pin has an end surface that is partially slanted. By operating a bellow, the pin can be moved so that its partially slanted end surface contacts, and coacts with, the tang of the tool so as to lift the tool upwardly into the tool holder.
The present invention provides a new press brake tool holder, which overcomes limitations of common press brake tool holders. In some particularly advantageous embodiments, the tool holder is suitable for hydraulic control.